Metal-containing neutral and overbased salicylates based on styrenated salicylic acid

ABSTRACT

An engine oil is disclosed that comprises a lubricating oil, and an overbased alkaline earth salicylate detergent of the structure:  
                 
 
     wherein:  
     X is  
                 
 
     R 1  is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, and substituted or unsubstituted aryl;  
     R 2 , R 3 , R 4 , R 5 , and R 6  are independently selected from the group consisting of hydrogen, X, and innocuous functional groups;  
     a and b are independently selected integers ≧0 and a+b ≧8;  
     m is 2; and  
     M is an alkaline earth metal.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to engine oils. More particularly,the present invention relates to overbased detergents for use in engineoils, especially metal-containing neutral and overbased salicylatesbased on styrenated salicylic acid that provide excellent detergency andclarity in a lubricating oil, and to a method for making suchdetergents.

[0003] 2. Description of Related Art

[0004] Among the materials that impart detergency to lubricating oils tokeep internal engine parts clean and reduce sludge formation in the oilare overbased detergents, particularly calcium sulfonates. Thesesulfonates are known to be useful as additives for lubricating oils,particularly as a crankcase engine oil for internal combustion engines.

[0005] It is known that by use of such overbased detergents equivalentdetergency characteristics can be obtained with a lower concentration ofadditive in a lubricating oil—the higher the alkaline reserve of anadditive, the larger the quantity of acidic combustion productsaccumulated in the oil to which the additive is added that can beneutralized by the additive. The measurement of alkaline reserve isreported as total base number (TBN) which is the number of milligrams ofpotassium hydroxide equivalent to the amount of acid required toneutralize the alkaline constituents present in one gram of sample. Anadditive having a total base number higher than can be obtained fromcalcium petroleum sulfonate alone is commonly said to be “overbased” or,alternatively, is said to be “superbasic”.

[0006] Overbased calcium sulfonates are generally produced bycarbonating a mixture of hydrocarbons, sulfonic acid, calcium oxide, orcalcium hydroxide and promoters, such as methanol and water. Incarbonation, the calcium oxide or hydroxide reacts with the gaseouscarbon dioxide to form calcium carbonate. The sulfonic acid isneutralized with an excess of CaO or Ca(OH)₂ to form the sulfonate.Known processes for overbasing calcium sulfonates produce high alkalinereserves of TBN of 300 to 400 mg KOH/gm or higher, which enables theformulator to use lower amounts of additive while maintaining equivalentdetergency to protect the engine adequately under conditions of highacid formation in the combustion process.

[0007] The calcium carbonate component of the overbased calciumsulfonate forms the core of a calcium sulfonate micellar structure. Thecalcium carbonate is either in the amorphous form or one or more of itscrystalline forms, such as calcite.

[0008] The lubricating oil art, particularly as directed to automotivecrankcase and other engine oils, mandates a clear or substantially hazefree product for requisite consumer aesthetics and acceptance. This needpreviously precluded the use of detergents with haze producingcrystalline calcium carbonate.

[0009] It was recognized in U.S. Pat. No. 4,995,993 that large micellarcrystalline calcium carbonate structures caused haze, and overbasedsulfonate products containing crystalline calcium carbonates were alwaysundesirable and therefore crystallization was to be avoided at allcosts.

[0010] In “Colloidal Anti-wear Additives 2. Tribological Behavior ofColloidal Additives in Mild Wear Regime,” J. L. Mansot et al., Colloidsand Surfaces A: Physico Chemical and Engineering Aspects, 75 (1993), pp.25-31, it is indicated that for certain forms of an overbased sulfonatecontaining an amorphous calcium carbonate core, when in a 2% by weightdispersion in dodecane, and subjected to metallic friction surfaces, thecalcium carbonate forms a polycrystalline film adherent to the metallicfriction surfaces, which resultantly provides anti-wear protection.Mansot et al. thereby taught providing an overbased calcium sulfonatewith an amorphous micellar structure that would then, under a mild wearregime, undergo transformation to microcrystalline agglomerates throughan amorphous intergranular phase.

[0011] WO 0004113 discloses a process for producing soluble overbasedcalcite-containing detergents that are suitable for use in engine oilformulations.

[0012] U.S. Pat. No. 4,617,135 discloses a process for the preparationof overbased oil soluble magnesium sulfonates comprising contacting anacidic gas at a temperature between about 50° F. up to the refluxtemperature of the mixture, with a mixture consisting essentially of asulfonic acid or salt thereof, a volatile aliphatic or aromatic orchlorinated hydrocarbon solvent, a non-volatile diluent oil, a lightmagnesium oxide, water, methanol and combination of promoters, whereinthe first promoter is one selected from an oil soluble naphthenic acidand an oil soluble carboxylic acid or salt thereof; and a secondpromoter being one selected from:

[0013] wherein X is one of H, OH, NH₂, CO₂H, OCOCH₃ and SH, and Y is oneof H, CH₃ and CH₂CH₃, wherein the second promoter is less oil solublethan the first promoter; and (b) a water soluble C₁-C₆ carboxylic acid.The volatile components are stripped from the reaction mixture afterabsorption of the acidic gas is completed, to give an overbasedmagnesium sulfonate. Relatively small amounts of about 1.0 to 1.5% ofthe combined promoters produce overbased magnesium sulfonates ofexceptionally high alkalinity value up to 500 or more, with minimumsediment.

[0014] U.S. Pat. No. 4,647,387 discloses an engine or lubricating oilcontaining 0.03 to 0.3% by weight of a succinic anhydride promoterreaction product for an overbased magnesium sulfonate, based on thepresence of 0.5% by weight of Mg metal in the oil, and wherein theweight of the reaction product is commensurately proportional to theweight of Mg metal in the oil, and which oil is free of post sulfonateformation water-tolerance additives, nevertheless passes the rigorousCummins water tolerance test. Copromoters such as a naphthenic acidand/or a salicylic acid may be employed.

[0015] U.S. Pat. No. 4,748,259 discloses mixtures of a metal salt offormula

[0016] and a metal salt of formula

[0017] in which formulae, Me is a metal ion of valency n, n is 2, 3 or4, and each of the rings A and B independently of the other isunsubstituted or substituted by halogen, lower alkyl, lower alkoxy or anα-methylbenzyl radical, are prepared by reacting 2 moles of salicylicacid with at least 2 moles of a styrene compound of formula

[0018] and at least 2 moles of a styrene compound of formula

[0019] in which formulae, the benzene rings A′ and B′ are unsubstitutedor substituted by halogen, lower alkyl or lower alkoxy, in the presenceof an aromatic sulfonic acid, and, in a further step, reacting 2n molesof the resultant mixture of the salicylic acid compound of formula

[0020] and the salicylic acid compound of formula

[0021] in which formulae, A and B are as defined above, with 2 moles ofthe salt of an n-valent metal of an inorganic acid or of a loweraliphatic carboxylic acid, where n has the given meaning. The mixturesof metal salts are used as color formers in pressure- and heat-sensitiverecording materials.

[0022] U.S. Pat. No. 4,810,398 discloses a basic alkaline earth metalsalt of a blend of organic carboxylic acids that is prepared by (a)preparing a mixture of one equivalent of the blend of organic carboxylicacids and more than one equivalent of an alkaline earth metal hydroxideand/or oxide in a hydrocarbon solvent; (b) introducing carbon dioxideinto the mixture obtained in an amount of at least 0.5 equivalent carbondioxide per equivalent of excess alkaline earth metal; and (c) removingresidual solids, if any, and an aqueous layer, if any, whereby the blendof organic carboxylic acids comprises a C₈₋₃₀ alkyl salicylic acid andone or more alkanecarboxylic acids in which the alkyl moiety is branchedand has from 4 to 40 carbon atoms. Such a salt has dispersant propertiesand is said to be suitable for use in lubricating oil and fuelcompositions.

[0023] U.S. Pat. No. 4,832,857 discloses a process for incorporatingmolybdenum into overbased alkaline earth metal and alkali metalsulfonates, phenates and salicylates. The incorporation is a postaddition of molybdenum into a previously prepared overbased composition.The resulting composition containing molybdenum is said to have areproducible TBN and to be gel-free, haze-free, precipitate-free, andcommercially acceptable for use in lubricating oil compositions.

[0024] U.S. Pat. No. 4,869,837 discloses a process for the preparationof a basic alkaline earth metal salt of a blend of organic carboxylicacids, which comprises (a) preparing a mixture of one equivalent of theblend of organic carboxylic acids and more than one equivalent of analkaline earth metal hydroxide and/or oxide in a hydrocarbon solvent;(b) introducing carbon dioxide into the mixture obtained in an amount ofat least 0.5 equivalent carbon dioxide per equivalent of excess alkalineearth metal; and (c) removing residual solids, if any, and an aqueouslayer, if any, whereby the blend of organic carboxylic acids comprisesan oil-soluble alkyl salicylic acid and one or more hydrocarbonsubstituted succinic acids or anhydrides, in which the hydrocarbonradical has a number average molecular weight from 120 to 5000.

[0025] U.S. Pat. No. 5,075,416 discloses a process for the preparationof an aromatic hydrocarbon resin modified with aromatic carboxylic acidscomprising suspending methane sulfonic acid and at least one aromaticcarboxylic acid in an aliphatic solvent and slowly proportioning atleast one unsaturated aromatic hydrocarbon into the suspension underpolymerization conditions and their salts.

[0026] U.S. Pat. No. 5,225,588 discloses alkylating hydroxybenzoates,such as methylsalicylate, by reacting a hydroxybenzoate with apolyalphaolefin in the presence of a catalytic amount of SnCl₄.

[0027] U.S. Pat. No. 5,415,792 discloses overbased alkyl alkylsalicylate that are said to be useful additives for lubricating oilcompositions that impart detergency and dispersancy to the lubricatingoil composition and provide for alkalinity reserve.

[0028] U.S. Pat. No. 5,647,896 discloses a color-developing agentcomprising a multivalent metal salt of a salicylic acid derivative and asulfonated phenol and/or a metal salt thereof and having excellentinitial and ultimate color-developing capacities and improvedwaterproofness; and a color-developing sheet making use of thecolor-developing agent.

[0029] U.S. Pat. No. 5,734,078 discloses a process for the production ofan alkyl salicylic acid in which the alkyl substituent has at least 6carbon atoms, comprising reacting salicylic acid with an olefin havingat least 6 carbon atoms at elevated temperature in the presence ofsulphuric acid as a catalyst. Lubricating oil additives comprising ametal salt of such alkylated salicylic acids and a process for makingthem are also disclosed.

[0030] U.S. Pat. No. 5,744,430 discloses a composition having therein abase oil with a specified kinematic viscosity and with a specified totalamount of aromatics, comprising, in specified amounts based on the totalweight of the composition: (b) an alkaline earth metal salicylatedetergent; (c) a zinc dialkyldithiophosphate; (d) a succinimide ashlessdispersant containing a polybutenyl group having a specifiednumber-average molecular weight; (e) a phenol ashless antioxidant; (f) amolybdenum dithiocarbamate friction modifier; and (g) a viscosity indeximprover in such an amount that the kinematic viscosity of saidcomposition ranges from 5.6 to 12.5 mm²/s at 100° C.

[0031] U.S. Pat. No. 6,197,075 discloses an overbased magnesiumcomposition deposit control additive for residual fuel oils and turbinefuels that is an overbased magnesium sulfonate, carboxylate or phenateor mixtures thereof containing at least 14% and upwards to about 18% byweight of magnesium and containing a succinic anhydride and lowercarboxylic acid co-promoter reaction product. The additive when added tofuel oils, such as residual fuel oils containing high asphaltenes,reduces, if not eliminates, magnesium/asphaltene deposits or sedimentand the consequential plugging of filters. The additive also reduces, ifnot eliminates, vanadium caused corrosion in the turbine. Also disclosedis a process for preparing the overbased composition or deposit controladditive, wherein the overbasing reaction incorporates the combinationof a lower carboxylic acid, preferably acetic acid and a succinicanhydride, preferably dodecenyl succinic anhydride, as the co-promoter.

[0032] U.S. Pat. No. 6,303,550 discloses a lubricating oil compositioncomprising a di-block copolymer of poly(monovinyl aromatic hydrocarbon)and hydrogenated poly(conjugated diene) as a dispersant additive. Thedi-block copolymer preferably comprises poly(monovinyl aromatichydrocarbon) in the molecular weight range 8,000-30,000. The diblockcopolymers are said to be useful as dispersant additives in lubricantoils, reduce heavy metal corrosion, reduce degradation of elastomericseals and are less sensitive to the presence of over-based detergents.

[0033] There remains a need in the art for a lubricating oil detergentwith inherent improved high temperature detergency which alsonecessarily has commercially acceptable levels of minimal haze, or areessentially haze free, and acceptable minimal levels of turbidity. Inparticular, there remains a need for an automotive oil having improveddetergency and antioxidant properties for use as a crankcase engine oil.

[0034] The compositions of this invention also are suitable for use ineither low or medium speed engines especially marine diesel engines.Typically such engines are 4 stroke trunk piston engines having anengine speed of 50-1000 RPM. The engine can also be a 2 stroke crosshead engine having a speed 40-1000 RPM.

SUMMARY OF THE INVENTION

[0035] A novel salicylate detergent has been developed with outstandingdetergency and anti-oxidant properties. While the current art utilizes ahydrocarbon backbone typically derived from an α-olefin having from 8 to20 carbons, it has now been found that alkyl salicylic acid derived fromthe alkylation of salicylic acid with styrene makes suitable salicylicacid that can be used to make metal based detergent additives.

[0036] The neutralization and subsequent overbasing of neutral saltresults in alkaline detergents, such as calcium or magnesiumsalicylates, that have detergency and anti-oxidant properties superiorto existing salicylate detergents. Thus, the present invention isdirected to the use of salicylic acid having multi-styrenated chains,which provide oil solubility, in the manufacture of oil soluble metaldetergents.

[0037] More particularly, the present invention is directed to an engineoil comprising a lubricating oil, and an overbased alkaline earthsalicylate detergent of the structure:

[0038] wherein:

[0039] X is

[0040] R¹ is selected from the group consisting of hydrogen, substitutedor unsubstituted alkyl, and substituted or unsubstituted aryl;

[0041] R², R³, R⁴, R⁵, and R⁶ are independently selected from the groupconsisting of hydrogen, X, and innocuous functional groups;

[0042] a and b are independently selected integers ≧0 and a+b≧8;

[0043] m is 2; and

[0044] M is an alkaline earth metal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] The alkaline earth metal salicylate detergents of the presentinvention suitably include a calcium salicylate detergent, a magnesiumsalicylate detergent, or a mixture thereof. In addition, thesedetergents can be neutral alkaline earth metal salicylates, overbasedalkaline earth metal salicylate, or combinations thereof. The neutralalkaline earth metal salicylate as used herein is a salt in which thearomatic compound-substituted salicylic acid is neutralized withequivalent moles of an alkaline earth metal hydroxide. Such a neutralalkaline earth metal salicylate can be represented by the followinggeneral formula (I):

[0046] wherein:

[0047] X is

[0048] R¹ is selected from the group consisting of hydrogen, substitutedor unsubstituted alkyl, and substituted or unsubstituted aryl;

[0049] R², R³, R⁴, R⁵, and R⁶ are independently selected from the groupconsisting of hydrogen, X, and innocuous functional groups;

[0050] a and b are independently selected integers ≧0 and a+b≧8,preferably in the range of from 8 to 40;

[0051] m is 2; and

[0052] M is an alkaline earth metal, preferably calcium or magnesium.

[0053] Where R¹ is alkyl, it is preferred that it be lower alkyl, i.e.,methyl, ethyl, propyl, butyl, or an isomer of propyl or butyl, e.g.,tert-butyl. It is preferred that R¹ be hydrogen or methyl.

[0054] Where R¹ is substituted, it may be substituted with any innocuousmoiety. As employed herein, the term “innocuous” is intended to mean amoiety that does not adversely affect the desired properties of thealkaline earth metal salicylate detergent, although they may, of course,provide beneficial effects.

[0055] Where R¹ is aryl, it is preferred that it be aryl of from 6 to 14carbon atoms, e.g., phenyl, biphenyl, naphthyl, anthracyl, phenanthryl,and the like. More preferably, where R¹ is aryl, it is substituted orunsubstituted phenyl. Again, those skilled in the art will understandthat any substituents will be innocuous, as defined above.

[0056] Those skilled in the art will also recognize that X in the abovestructural formula can be considered a styrenic-type moiety. Examples ofsuch styrenic-type moieties include, but are not limited to, styrene; 2,3,or 4-methylstyrene; 2 or 4-ethylstyrene; 3 or 4-isopropylstyrene;4-n-butylstyrene; 4-t-butylstyrene, 4-cyclohexylstyrene; 4-octylstyrene;2,4-dimethylstyrene; 2,5,dimethylstyrene; 3- or 4-methoxystyrene,4-ethoxystyrene; α-methylstyrane; α-ethylstyrene; α-n-butylstyrene;α-isobutylstyrene; 4-phenyistyrene; 4-fluorostyrene; and the like.Styrene is preferred.

[0057] Overbased alkaline earth metal salicylates may be obtained byoverbasing a neutral alkaline earth metal salicylate to produce analkaline earth metal carbonate, such as calcium carbonate and magnesiumcarbonate, or an alkaline earth metal borate, such as magnesium borate.

[0058] The base number of the metal salicylate detergent is notparticularly limited; however, the base number is normally in the rangeof from about 60 to about 350 mg KOH/g, preferably from about 150 toabout 350 mg KOH/g.

[0059] It has been pointed out above that a+b in the formula is greaterthan 7, i.e., 8 or more, preferably 8 to 40, more preferably 8 to 20.Where a+b is at the lower end of this range, e.g., 8, it has been foundthat the solubility of the compound in oil will be less than willnormally considered desirable. As more vinyl aromatic units are added tothe chain attached to the salicylic acid moiety, i.e., as a+b increases,oil solubility will increase. If it is desired to use a compound whereina+b is about 8, oil solubility can be improved by the addition ofanother overbased compound, e.g., overbased calcium sulfonate. Fordetergent additives of the present invention having sufficient vinylaromatic groups present to render the compound oil soluble, theinclusion of the overbased calcium sulfonate or the like can bedispensed with.

[0060] In general, the process of preparing the overbased calciumsalicylates of the present invention comprises reacting a solution ofstyrenated salicylic acids and, optionally, calcium sulfonate orsulfonic acid (for convenience, the following discussion will focus oncalcium compounds, but those skilled in the art will readily comprehendthat, by analogy, the process can be applied to magnesium compounds, aswell as to calcium and magnesium mixtures) in oil with a slurry ofcalcium oxide or hydroxide and bubbling carbon dioxide through thereaction mixture, thereby incorporating an excess of calcium carbonateinto the calcium salicylate and, if present, calcium sulfonate, whichconfers the desired reserve alkalinity to the product. In this process,it has been found advantageous to add a low molecular weight alcohol,such as methanol, and water to promote the formation of a micellardispersion of calcium carbonate.

[0061] Calcium hydroxide when used commercially as the sole reservealkalinity agent in the reaction mixture is used in substantial excessin order to achieve a high TBN product.

[0062] A dispersant is an optional component of the process and productfor the calcite overbased detergent. A preferred dispersant is thereaction product of hydrocarbyl-substituted succinic acid or anhydridewith amines containing at least one primary or secondary amino nitrogen,e.g., the polyalkylene polyamines fulfill this requirement as do thesubstituted polyalkylene polyamines, and for that matter, ammonia. Thebis-succinimides are also useful as optional dispersants. Thebis-succinimides are prepared by the reaction of hydrocarbyl-substitutedsuccinic acid or anhydride with an amine containing at least two primaryand/or secondary nitrogens. Such bis-succinimides are, for example, thepolyisobutenyl bis-succinimides of ethylene diamine, diethylenetraimine, or triethylene tetramine, or tetraethylene pentamine orN-methyldipropylene triamine, etc. (e.g., Benoit, U.S. Pat. No.3,438,899). The various above-described dispersing agents can be usedalone or in mixtures.

[0063] The overbased calcium salicylate product of the present inventionhas an amorphous micellar structure. The overbased calcium salicylate,or like overbased detergent, is a stable dispersion of amorphous calciumcarbonate.

[0064] The overbased calcium salicylate detergent of the presentinvention may be added to engine or lubricating oils in detergentamounts of about 0.1 to 25% by weight or more, and are soluble in suchoils at room temperature if a+b is high enough or if overbased calciumsulfonate is present, where a+b is low.

[0065] The present invention is applicable to a wide variety oflubricating oils. The lubricating oil can be composed of one or morenatural oils, one or more synthetic oils, or mixtures thereof. Naturaloils include animal oils and vegetable oils (e.g., castor, lard oil),liquid petroleum oils, and hydrorefined, solvent-treated or acid-treatedmineral lubricating oils of the paraffinic, naphthenic and mixedparaffinic types. Oils of lubricating viscosity derived from coal orshale are also useful base oils.

[0066] Synthetic lubricating oils include hydrocarbon oils andhalo-substituted hydrocarbon oils, such as polymerized andinterpolymerized olefins (e.g., polybutylenes, polypropylenes,propylene-isobutylene copolymers, chlorinated polybutylenes,poly(1-hexenes), poly (1-octenes), poly(1-decenes)); alkylbenzenes(e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,di(2ethylhexyl)benzenes); polyphenyls (e.g. biphenyls, terphenyls,alkylated polyphenols); alkylated diphenyl ethers and alkylated diphenylsulfides and the derivatives, analogs, and homologs thereof.

[0067] Alkylene oxide polymers and interpolymers and derivatives thereofwhere the terminal hydroxyl groups have been modified by esterification,etherification, etc., constitute another class of known syntheticlubricating oils. These are exemplified by polyoxyalkylene polymersprepared by polymerization of ethylene oxide or propylene oxide, thealkyl and aryl ethers of these polyoxyalkylene polymers (e.g.,methylpolyisopropylene glycol ether having an average molecular weightof 1000, diphenyl ether of polyethylene glycol having a molecular weightof 500-1000, diethyl ether of polypropylene glycol having a molecularweight of 1000-1500); and mono- and polycarboxylic esters thereof, forexample, the acetic acid esters, mixed C₃-C₈ fatty acid esters and C₁₃oxo acid diesters of tetraethylene glycol.

[0068] Another suitable class of synthetic lubricating oils comprisesthe esters of dicarboxylic acids (e.g., phthalic acid, succinic acids,alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaicacid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleicacid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids)with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycolmonoether, propylene glycol). Specific examples of these esters includedibutyl adipate, di-(2-ethylhexyl) sebacate, di-n-hexyl fumarate,dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctylphthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyldiester of linoleic acid dimer, and the complex ester formed by reactingone mole of sebacic acid with two moles of tetraethylene glycol and twomoles of 2-ethylhexanoic acid.

[0069] Esters useful as synthetic oils also include those made from C₅to C₁₂ monocarboxylic acids, and polyols and polyol ethers such asneopentyl glycol, trimethylolpropane, pentaerythritol,dipentaerythritol, and tripentaerythritol.

[0070] Silicon-based oils such as the polyalkyl-, polyaryl-,polyalkoxy-, and polyaryloxysiloxane oils and silicate oils compriseanother useful class of synthetic lubricants; they include tetraethylsilicate, tetraisopropyl silicate, tetra-(2-ethyhexyl)silicate,tetra-4-methyl-2-ethylhexyl) silicate, tetra-(p-tert-butyphenyl)silicate, hexa-(4-methyl-2-pentoxy) disiloxane, poly(methyl)siloxanesand poly(methylphenyl) siloxanes. Other synthetic lubricating oilsinclude liquid esters of phosphorus-containing acids (e.g., tricresylphosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid)and polymeric tetrahydrofurans.

[0071] Unrefined, refined, and rerefined oils can be used in thelubricants of the present invention. Unrefined oils are those obtaineddirectly from a natural or synthetic source without further purificationtreatment. For example, a shale oil obtained directly from retortingoperations, a petroleum oil obtained directly from distillation or esteroil obtained directly from an esterification process and used withoutfurther treatment would be an unrefined oil. Refined oils are similar tothe unrefined oils except they have been further treated in one or morepurification steps to improve one or more properties. Many suchpurification techniques, such as distillation, solvent extraction, acidor base extraction, filtration, and percolation are known to thoseskilled in the art. Rerefined oils are obtained by processes similar tothose used to obtain refined oils, but applied to oils that have beenalready in service. Such rerefined oils are also known as reclaimed orreprocessed oils and often are additionally processed by techniques forremoval of spent additives and oil breakdown products.

[0072] The invention is particularly directed to engine oil formulationsand additives therefor. As used herein the term “engine oil” means alubricating oil that may be useful in an engine oil, and by way ofexample, includes an automotive oil or diesel engine oil. Thelubricating oil compositions of the present invention are also suitablefor lubrication of marine diesel engines including 4 stroke trunk pistonengines and 2 stroke cross head engines.

[0073] The formulated oil should have a viscosity in the lubricatingviscosity range, typically about 45 SUS at 100° F., to about 6000 SUS at100° F. The lubricating oil also contains one or more overbased alkalineearth metal detergents, at least one of which is a metal-containingneutral and overbased salicylate based on styrenated salicylic acid asdescribed herein. The detergent components collectively comprise aneffective amount, which usually lies in a range of 0.01 wt. % up to asmuch as 25 wt. %, preferably 0.1-10 wt. %, more preferably 0.1 to 5.0%.Unless indicated otherwise herein, all weight percentages are by weightof the entire lubricating oil composition.

[0074] The advantages and the important features of the presentinvention will be more apparent from the following examples.

EXAMPLES Comparative Example A Overbasing 2:1 Molar Ratio Styrene:Salicylic Acid

[0075] One hundred parts of 2:1 molar styrenated salicylic acid is mixedwith 200 parts of VMP naphtha and 68 parts of 100 viscosity paraffinicoil. To this are added 10 parts of neutral calcium sulfonate, 12 partsof methanol, and 30 parts of lime. The mixture is heated to 130-150° F.(54-66° C.) and carbonated with carbon dioxide at a rate of 150mL/minute for 20 minutes.

[0076] Heat is lost during carbonation and the reaction mixtureseparates into two phases—one of which is insoluble in VMP naphtha.

Comparative Example B

[0077] Comparative Example A was repeated, but the aromatic solventxylene was substituted for the VMP naphtha, and 200 viscosity naphthenicoil substituted for the paraffinic oil.

[0078] In this case, the carbonation step resulted in an exothermicreaction. The reaction product was filtered to remove unreacted solids,and heated to 380° F. (193° C.), to remove methanol and xylene.

[0079] The final product was fluid at 380° F., but when cooled to under200° F. (93° C.), it solidified.

Comparative Example C Overbasing 4:1 Molar Ratio Styrene: Salicylic Acid

[0080] One hundred parts of 4:1 molar styrenated salicylic acid is mixedwith 200 parts of VMP naphtha and 68 parts of 200 viscosity naphthenicoil. To this mixture is added 10 parts of neutral calcium sulfonate, 12parts of methanol, and 30 parts of lime. The mixture is heated to130-150° F. and carbonated with carbon dioxide at a rate of 150mL/minute for 20 minutes.

[0081] The carbonation step resulted in an exothermic reaction. However,the final product collapsed into two phases while being filtered.

Comparative Example D

[0082] One hundred parts of 4:1 molar styrenated salicylic acid is mixedwith 200 parts of VMP naphtha and 60 parts of 200 viscosity naphthenicoil. To this mixture is added 60 parts of neutral calcium sulfonate, 12parts of methanol, and 30 parts of lime. The mixture is heated to130-150° F. and carbonated with carbon dioxide at a rate of 150mL/minute for 20 minutes. The product is then filtered to remove excesssolids and heated to 380° F. to remove methanol and VMP naphtha.

[0083] The carbonation resulted in an exothermic reaction. The finalproduct was fluid, with a viscosity of 39 cst, and a TBN of 121;however, it exhibited poor solubility at 10% in 500 viscosity paraffinicoil.

Example 1 Calcium and Magnesium Salicylates Using Styrenated SalicylicAcid

[0084] This example describes a method to make alkyl styrene salicylicacid.

[0085] Thirty four grams (0.25 mole) of salicylic acid is added to areactor, followed by 5 grams of p-toluenesulfonic acid, and heated to120° C. to form a partial melt. A quantity of 312 grams (3 moles) ofstyrene is added dropwise over two hours, keeping the temperaturebetween 145-160° C. After the complete addition of the styrene, theclear brown solution is maintained at 155° C. for one hour.

Example 2 Overbasing 8:1 Molar Styrene: Salicylic Acid

[0086] Sixty parts of 8:1 molar styrenated salicylic acid is mixed with200 parts of VMP naphtha and 100 parts of 200 viscosity naphthenic oil.To this mixture is added 36 parts of neutral calcium sulfonate, 12 partsof methanol, and 40 parts of lime. The mixture is heated to 130-150° F.and carbonated with carbon dioxide at a rate of 200 mL/minute for 25minutes. The product was then filtered to remove excess solids, andheated to 380° F. to remove methanol and VMP naphtha.

[0087] The carbonation resulted in an exothermic reaction. The finalproduct was fluid, with a viscosity of 12 cst., and a TBN of 154.

[0088] Visual inspection of a 10 % solution of this material in 500viscosity oil showed improved clarity over the product of ComparativeExample D, but the resulting solution was still not bright and clear.

Example 3

[0089] Sixty-eight parts of 8:1 molar styrenated salicylic acid is mixedwith 200 parts of VMP naphtha and 70 parts of 200 viscosity naphthenicoil. To this mixture is added 76 parts of neutral calcium sulfonate, 12parts of methanol, and 43 parts of lime. The mixture is heated to130-150° F. and carbonated with carbon dioxide at a rate of 200mL/minute for 30 minutes. The product is then filtered to remove excesssolids and heated to 380° F. to remove methanol and VMP naphtha.

[0090] The carbonation resulted in an exothermic reaction. The finalproduct was fluid, with a TBN of 181.

[0091] Solubility at 10% in 500 viscosity oil was excellent, giving aproduct that was bright and clear.

Example 4

[0092] The alkyl salicylic acid of Example 1 is used to prepare anoverbased calcium salicylate as shown below.

[0093] One hundred grams of styrene salicylic acid from Example 1 isadded to a mixing vessel followed by 150 grams of naphtha and 100 gramsof 600 SUS base oil. The mixture is agitated slowly and 20 grams of aneutral calcium sulfonate is charged, followed by 14 grams of methanoland 35 grams of hydrated lime.

[0094] The temperature is adjusted to 60° C. and carbon dioxide isintroduced at 200 mL/minute for 30 minutes. Upon completion of thecarbonation, the dark brown liquid is filtered and distilled to 220° C.to produce a clear brown solution of the desired calcium carbonateoverbased calcium salicylate. The total alkalinity of the final productis about 190.

Example 5

[0095] The styrene salicylic acid of Example 1 is reacted with anoverbased calcium sulfonate as shown below to produce a clear brownsolution with total alkalinity of 300.

[0096] Fifty grams each of styrene salicylic acid and 500 TBN calciumsulfonate is mixed and heated to 40° C., whereupon 75 grams of naphthaand 15 grams of methanol are added. The mixture is mixed at 60° C. forone hour then heated to 220° C. to remove the volatiles. The product,when tested in the high temperature detergency panel coker test,resulted in 10.7 milligrams of deposit.

[0097] In view of the many changes and modifications that can be madewithout departing from principles underlying the invention, referenceshould be made to the appended claims for an understanding of the scopeof the protection to be afforded the invention.

What is claimed is:
 1. An engine oil comprising a lubricating oil, andan overbased alkaline earth salicylate detergent of the structure:

wherein: X is

R¹ is selected from the group consisting of hydrogen, substituted orunsubstituted alkyl, and substituted or unsubstituted aryl; R², R³, R⁴,R⁵, and R⁶ are independently selected from the group consisting ofhydrogen, X, and innocuous functional groups; a and b are independentlyselected integers ≧0 and a+b≧8; m is 2; and M is an alkaline earthmetal.
 2. The engine oil of claim 1 wherein M is selected from the groupconsisting of calcium and magnesium
 3. The engine oil of claim 1 whereinR¹ is hydrogen or methyl.
 4. The engine oil of claim 1 wherein R¹ issubstituted or unsubstituted aryl.
 5. The engine oil of claim 4 whereinR¹ is substituted or unsubstituted phenyl.
 6. The engine oil of claim 1wherein X is selected from the group consisting of styrene; 2, 3,or4-methylstyrene; 2 or 4-ethylstyrene; 3 or 4-isopropylstyrene;4-n-butylstyrene; 4-t-butylstyrene, 4-cyclohexylstyrene; 4-octylstyrene;2,4-dimethylstyrene; 2,5,dimethylstyrene; 3- or 4-methoxystyrene,4-ethoxystyrene; α-methylstyrane; α-ethylstyrene; α-n-butylstyrene;α-isobutylstyrene; 4-phenylstyrene; and 4-fluorostyrene.
 7. The engineoil of claim 6 wherein X is styrene.
 8. The engine oil of claim 1wherein the base number is in the range of from about 60 to about 350 mgKOH/gram.
 9. The engine oil of claim 1 wherein a+b is 8 to
 40. 10. Anengine oil comprising a lubricating oil, and an overbased alkaline earthsalicylate detergent of the structure:

wherein: X is styrene; a and b are independently selected integers ≧0and a+b is 8 to 40; m is 2; and M is an calcium or magnesium.